The conduct of business today requires the efficient and rapid handling and movement of documents. Documents, such as mail envelopes by way of example, often must be machine read, coded, transported and sorted for rapid delivery from the generator of the document to its recipient. In certain apparatus, once the content of a document is read or deciphered, further handling applies a machine readable code to the document face, the code is machine read, and the document is then sorted by being mechanically deposited in a pre-designated bin. The designation of the bin may be a function of the code imprinted on the document. All of these functions are preferably performed while the document is travelling at very high speeds, such as 150 to 200 inches per second, through the document handling apparatus.
One such document handling apparatus of the type described above, which is described here by way of example, is used by the postal service in its facilities to (1) rapidly feed mail envelopes into an optical scanning device which reads the address printed on the envelope and selects a nine digit zip code corresponding to the address from a digitized national zip code directory stored in memory, (2) print a bar code on the envelope corresponding to the zip code selected from the data storage bank, (3) read the bar code to verify its accuracy, and (4) deposit the envelope in a depository or bin which receives and sorts the mail corresponding to the zip code read by the optical reader and imprinted on the envelope. The present invention relates to the document transport mechanism used in the sorter portion of the apparatus.
Prior sorting devices of the type described comprise an elongated linear moving flat belt upon which a series of envelopes (or other documents) are upright and singularly disposed. The sorter also comprises a series of opposed drive belt and idler roller assemblies which defines the path of the envelopes, and transports the envelopes to their appropriate bin. Each of these assemblies comprises a driving belt support on one side of the document path, and an idler roller support on the other side of the document path. The driving belt support includes a driving belt extending around a plurality of rollers, one of which is connected to a power source to rotate the driven roller and move the belt around the rollers. A portion of the moving belt extends in a linear direction above the horizontally extending belt and is adapted to abut one surface of the envelope along a predetermined extent, approximately 8 to 12 inches.
The idler roller support is disposed on the opposite side of the document path relative to the drive roller support, and includes a plurality of idler rollers mounted for horizontal rotation in the same plane, and adjacent the moving belt of the driving belt support. The idler rollers are adapted to contact the opposite face of the document which is in contact with the feed belt, whereby the document is substantially firmly held between the feed belt and the idler rollers.
At the end of the document path defined by each pair of opposed driving belt support and idler roller support are pairs of deflectors which are mechanically operated responsive to electronic sensing of the appropriate destination of the document to either (1) direct a document out of the document path described above and into a storage receptacle or bin, or (2) allow the document to pass along the document path into the next serially disposed drive belt and idler roller assemblies. The combinations of deflectors and drive belt and idler roller assemblies along the document path are substantially identical.
Since mail of various thicknesses must be transported and handled along the sorter document path described above, the width component of the document path must be variable, yet maintained under tension to grip the documents. Also, the distance between the feed belt and the idler rollers must be capable of manual release by an operator to clear up any document jam that may occur between the belt and idler rollers. Prior devices of this type rely on the resilient structure of the rollers to compensate for variable document thickness, and upon rigid lever connections to the idler rollers to withdraw the idler rollers in the event of a jam. These structures create two problems in high speed document transport systems which must be addressed: (1) the resiliency of the rollers and belt is incapable of making adjustments for various sized envelopes travelling at high speeds because the deformation of the rollers required by such mechanisms does not recover fast enough, causes jams, and tends to slow down the speed of document transport. Also, as the documents move along the document path at high speeds, the manual lever operating the jam control mechanism will constantly chatter back and forth, causing undesirable noise and wear and tear on the lever mechanism and its attendant parts.
Therefore, a primary object of the present invention is to provide a document transport system having opposed drive belt and idler roller assemblies which provide a variable width for the document path as documents of variable thickness are engaged and gripped between the moving belt and the idler rollers, without any of the shortcomings of the currently available devices noted above.
Yet another object of the present invention is to provide an idler roller assembly for a document transport system, which assembly includes a manually operated jam release lever which is operatively connected to the idler rollers through a lost motion connection in one direction, whereby movement and chatter of the lever arm is prevented upon normal operation of the document transport system.
An additional object of the invention is to provide a moveable idler roller support mechanism for a document transport system including moveable pivot mountings for the idler rollers which allow the idler rollers to move laterally to compensate for documents of varying thicknesses passing through the document transport system, and a manually operable lever operatively connected by a series of pulley and cable connections to the idler roller supports, whereby actuation of the lever arm causes corresponding movement of the idler rollers in a lateral direction, but lateral movement of the idler rollers under the influence of documents of varying thickness passing through the transport system does not cause corresponding movement or chatter of the manual lever arm.